The present invention relates to spray formulations. It is particularly well suited for application to insect repellent aerosol formulations that provide improved skin feel without unacceptably increasing the risk of clogging or undesired sedimentation.
A variety of formulations have been developed for spraying on human skin which are designed to be sprayed from an aerosol can or a pump sprayer. For example, a typical insect repellent spray formulation contains an insect repellent, a carrier solvent, a propellant gas (in the case of an aerosol spray), and minor amounts of other materials (e.g. fragrance, corrosion inhibitor and emollient).
Attempts have been made to add powdery materials (particularly corn starch) to such formulations so that the resulting spray has a smooth/dry feel on the skin. See generally U.S. Pat. No. 6,581,807. Unfortunately, powders such as starches tend to cake in aerosol cans when included in formulations of this type, and then form chunks that do not disperse easily even with shaking of the can/bottle prior to each use. This can clog the delivery tube and nozzle of the spraying device and cause unwanted sedimentation (which reduces the powder concentration in the delivered spray even when there is no clogging).
Complicating matters further is that any ingredient added to such a formulation must be suitable for the use on skin and adjacent clothing. Further, the ingredient must be compatible with other conventional spray formulation ingredients during long term storage. This has made resolving these concerns a challenging problem.
Thus, a need still exists to find ways to deliver spray formulations (particularly insect repellent aerosol spray formulations) having a smooth/dry skin feel, while avoiding clogging and sedimentation problems, and while maintaining repellency characteristics of the spray.